Traditionally, applications for a particular computing system are largely autonomous. Although applications take advantage of some operating system features and can be started by the operating system to perform specific tasks for users, the operating system has little or no control over how the applications implement the features or perform the tasks. Moreover, different applications, especially applications associated with different runtime platforms, may individually control aspects like window generation, layout and ordering, color schemes, fonts, and so forth. Accordingly, the traditional, uncoordinated approach to application implementation creates a disjointed “look and feel” that can inhibit users from having an entirely positive user experience with respect to the operating system.